1. Field of the Invention
The present invention relates to a laser machining apparatus and a laser machining method for performing laser machining while controlling reflected light.
2. Description of the Related Art
Laser machining is performed in accordance with machining conditions selected for material to be cut, the thickness of the material, and the like. At the beginning of a laser machining process, a strong reflected light often causes the laser machining to be interrupted or stopped. Techniques for avoiding troubles caused by reflected light are known, for example, by the following patent literature.
Japanese Unexamined Patent Publication (Kokai) No. 2014-117730 describes an invention in which, in a preparatory machining conducted before the laser machining, the laser beam is output on a piercing condition with varied focus positions, the position at which the reflected light is weakest is stored in a memory, and the piercing (bore making) is carried out at that position.
Japanese Examined Patent Publication (Kokoku) No. 4174267 describes an invention in which the laser beam is emitted in pulses before a piercing or cutting process and when the reflected light measured exceeds a prescribed value, the width of the laser beam pulse is shortened.
PCT International Publication No. 2013/014994 describes an invention in which the laser beam is output to a workpiece, and whether the preset machining condition is a proper one for the workpiece or not is determined by checking the reflected light.